Needle protection assemblies

ABSTRACT

An intravenous needle protection assembly has a channel-shape housing with two rails along which a needle assembly and a guard can be slid. The needle assembly carries a cannula assembly that can be slid off the needle assembly at a forward position along the housing. A rearwardly-extending, inclined resilient tab projects from the bottom of the guard and engages a locking surface at the rear edge of a recess when the guard is in the forward position. When the needle assembly is subsequently slid back to a rear position, the guard covers the tip of the needle at the forward end of the housing. A forwardly-extending resilient tab on the needle assembly then engages a locking surface at the rear of the housing to lock the needle assembly in position.

TECHNICAL FIELD

This invention relates to needle protection assemblies of the kindincluding a channel-shape protector housing having a slot opening alonga major part of the length of the housing, a needle assembly slidablealong the housing between a first position in which a tip of a needle islocated within the housing and a second position in which the tip of theneedle is exposed at one end of the housing and a cannula assemblymounted on the needle assembly such that it can be slid off the tip ofthe needle in the second position.

The invention is more particularly concerned with needle protectionassemblies for intravenous cannula insertion devices, or the like.

BACKGROUND ART

Intravenous cannula insertion devices of the over-the-needle kindcomprise a needle with a bevelled tip that projects by a short distancefrom the forward, patient end of an intravenous cannula. The cannula isinserted by pushing the needle tip into a vein, then sliding the cannulaforwardly off the tip of the needle, into the vein, and withdrawing theneedle from the rear end of the cannula. An example of such a device,including a tubular protector surrounding the device before use, isdescribed in EP-A-0054671. The protector has a longitudinal slot alongwhich the cannula hub is slid on insertion. After use, the needle iswithdrawn into the protector, leaving the cannula in the vein. Theprotector provides protection from needle-stick injury before and afteruse. It is common practice, however, for some clinicians to bend theneedle before use in order to give a preferred shape for introduction.In such a case, the tip of the needle can protrude from the slot of theprotector when it is withdrawn after use. This can provide a hazard tothe user.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an improved needleprotection assembly.

According to the present invention there is provided a needle protectionassembly of the above-specified kind, characterised in that the assemblyincludes a guard mounted on the needle assembly such that it isdisplaced forwardly to the one end of the housing when the needleassembly is slid to the second position, and a lock for retaining theguard at the one end of the housing when the needle assembly isretracted rearwardly to the first position, and that the guard coversthe slot in the housing in the region of the tip of the needle when theneedle assembly is retracted to the first position.

The lock preferably comprises a reslient catch on the guard and alocking surface on the housing. The resilient catch may be arearwardly-extending inclined tab. The needle protection assemblypreferably includes a second lock for locking the needle assembly in thefirst position after it has been retracted into the first position. Thesecond lock may be provided by a forwardly-extending inclined tab on theneedle assembly and a rearwardly-facing locking surface on the housing.When the guard is in the first position, the tab on the needle assemblymay engage an upper surface of the tab on the guard so that when theneedle assembly is slid forwardly, the tab on the guard deflects the tabon the needle assembly over the rearwardly-facing locking surface.

The guard preferably has a surface formation on an upper surface, theneedle assembly having a surface formation at one end of an arm, the armextending from a catch resiliently-mounted on the needle assembly, theneedle assembly being displaced from the first to the second position byengaging one surface of the catch so that its arm is urged downwardly,and the needle assembly being displaced from the second to the firstposition by engaging another surface of the catch so that its arm isurged upwardly and the surface formation on the arm clears the surfaceformation on the guard. The guard may have a lateral plate with anon-circular aperture, the cannula assembly extending through theaperture and the rear end of the cannula assembly being shaped such thatit can only pass through the aperture when oriented correctly. Thehousing may have a rail extending along its length, the needle assemblyand guard both engaging the rail.

BRIEF DESCRIPTION OF DRAWINGS

An intravenous needle protection assembly in accordance with the presentinvention, will now be described, by way of example, with reference tothe accompanying drawings, in which:

FIG. 1 is a partly sectional side elevation of the assembly in a firstposition;

FIG. 2 is an enlarged perspective view of a part of the housing of theassembly;

FIG. 3 is an enlarged perspective view of a part of the needle assembly;

FIG. 4 is an enlarged side elevation view of the cannula assembly;

FIG. 5 is an enlarged perspective view of the guard member;

FIG. 6 is a partly sectional side elevation of the needle protectionassembly in a second position;

FIGS. 7 and 8 are partly sectional side elevation views of the needleprotection assembly as the needle assembly is retracted to the firstposition; and FIG. 9 is a sectional side elevation of a modified housingfor the assembly.

BEST MODES FOR CARRYING OUT THE INVENTION

With reference to FIGS. 1 to 5, the intravenous needle protectionassembly comprises a protector housing 1 in which is mounted a needleassembly 2 supporting an intravenous cannula assembly 3 and a guard 4.The needle assembly 2 with the cannula assembly 3 and guard 4 areslidable along the housing 1.

The housing 1 is a U-shape channel of rigid plastics material with twolongitudinal rails 10 and 11 projecting outwardly along opposite sidesat the top of the housing. The top of the housing 1 is open along itslength to provide a longitudinal slot 12. At the forward end of thehousing a stop 13 projects upwardly from the floor of the housing tolimit the extent of forward displacement of the needle assembly.Immediately to the rear of the stop 13, there is a shallow recess 14with a vertical rear wall 15 that provides a first, forwardly-facinglocking surface. The housing 1 also has an aperture 16 in its floorlocated a short distance forwardly of the rear end of the housing. Theforward edge 17 of the aperture 16 provides a second, rearwardly-facinglocking surface. A second stop 18 projects from the floor of the housingat the rear end, to limit rearward displacement of the needle assembly2.

The needle assembly 2 comprises a hollow metal needle 20 with a bevelledtip 19 at its forward end and with a rear end moulded into a rigidplastics hub 21. The hub 21 is preferably transparent and is ofgenerally cylindrical shape having a bore 22 communicating with the borethrough the needle 20. The bore 22 is sealed at the rear end of the hub21 by a hydrophobic filter 22', which allows venting of gas but preventsescape of blood. At its forward end, the hub has a tapered projection23, which is makes a push fit in the rear of the cannula assembly 3. Onthe lower surface of the hub 21, just to the rear of the projection 23,there is a resilient locking catch 24 formed by a tab that inclinesforwardly and downwardly. The upper surface 25 of the hub is flat andextends forwardly as a bar 26 over the rear part of the projection 23.At the rear end of the hub 21, a carriage 27 extends laterally onopposite sides of the hub above the top of the housing 1. The undersideof the carriage 27 has a longitudinal recess 28 on each side in whichthe rails 10 and 11 are slidably received.

The hub 21 also includes an integral catch member 29 mounted on thecarriage 27 by means of a resilient pillar 30. The catch member 29 has aforwardly-extending arm 31 with a downwardly-projecting inclined tooth32 or similar surface formation at its forward end. The catch member 29extends upwardly to form a forward, finger-engaging surface 33 ofconcave shape and a rear, finger-engaging surface 34 of convex shape.

With reference now especially to FIG. 4, the cannula assembly 3 is ofconventional construction comprising a tubular plastics cannula 40 witha hub 41 at its rear end. A triangular wing 42 projects from the side ofthe hub 41 and encloses a branch bore 43 communicating between the borethrough the cannula 40 and a flexible, small bore tube 44. The rear endof the hub 41 is open and has two bayonet locking lugs 45 projectingfrom its outer surface.

The final component of the needle-protection assembly is the guard 4shown most clearly in FIG. 5. The guard 4 is a rigid plastics devicewith a flat horizontal plate 50 about 15 mm long, which extends abovethe top of the housing 1. The width of the plate 50 is slightly greaterthan that of the housing 1, the plate having longitudinal clips 51underneath each opposite edge, which engage on respective ones of therails 10 and 11. A short, laterally extending tooth 52 or similarsurface formation projects from the upper surface of the plate 50 abouthalf way along its length. The tooth 52 on the guard 4 is engaged by thetooth 32 on the catch 29 of the needle assembly 2 in the mannerdescribed later. At the forward end of the guard 4, there is a lateral,vertical plate 53 with a non-circular bayonet aperture 54. The aperture54 has a central, circular region 55 and radially enlarged regions 56above and below the circular region. The shape of the aperture 54 issuch that the rear of the hub 41 on the cannula assembly 3 can be pushedthrough the aperture if the lugs 45 are aligned with the enlargedregions 56. Withdrawal of the hub 41 through the aperture 54 isprevented if the lugs 45 are out of alignment with the enlarged regions56. A resilient locking catch formed by a tab 57 projects downwardlyfrom the vertical plate 53 and is inclined rearwardly.

Industrial Applicability

Prior to use, the components of the needle protection assembly areassembled together in the manner shown in FIG. 1. The cannula assembly 3is pushed fully onto the needle assembly 2 so that the tip 19 of theneedle 20 projects from the forward end of the cannula 40. The guard 4is locked onto the cannula assembly 3 with the lugs 45 to the rear ofthe vertical plate 53 and 90° out of alignment with the enlarged regions56. The bar 26 on the needle hub 21 engages the sides of the lugs 45,between which it is located, and thereby prevents rotation of thecannula hub 41.

The wing 42 of the cannula assembly 3 projects vertically upwards out ofthe slot 12 of the housing 1. The horizontal plate 50 of the guard 5extends rearwardly along the top of the needle hub 21 and is retained inposition by engagement of the tooth 32 on the catch 29 with the forwardedge of the tooth 52 on the guard 4. The catch 24 on the needle hub 21contacts the upper surface of the catch 57 on the guard 4. Both thecatches 24 and 57 project down into the aperture 16 so that the needleassembly 2 is retained at the rear end of the housing.

In this position, the guard 4 and cannula assembly 3 are securelyretained on the needle assembly 2. The needle assembly 2 is retained atthe rear end of the protector housing 1 with the tip 19 of the needle 20protected within the housing and spaced from the end of the housing byabout 1 cm. The catch 29 projects vertically out of the slot 12 of thehousing 1 for access by the user.

The needle assembly 2, with the guard 4 and the cannula assembly 3 canbe displaced forwardly to the position shown in FIG. 6 by pushing therear, convex surface 34 of the catch 29. There is an initial resistanceto forward movement of the needle assembly 1 because of engagement ofthe catches 24 and 57 in the aperture 16, which is sufficient to retainthe assemblies in position until manual pressure is exerted. Therearwardly-inclined catch 57 on the guard 4 deflects the catch 24 on theneedle assembly 1 upwardly so that it clears the forward locking edge 17of aperture 16. When the guard 4 reaches the forward end of the housing1, its catch 57 snaps down into the recess 14.

In the position shown in FIG. 6, the needle assembly 2 projects from theforward end of the housing so that the tip 19 of the needle 20 and thecannula 40 can be inserted in a vein in the usual way.

The user then withdraws the needle 20 by pushing against the concave,forward surface 33 of the catch 29. This rotates the catch in aclockwise sense about its pillar 30 so that the tooth 32 is lifted abovethe tooth 52 on the guard 4 and so that the needle assembly 2 can beslid rearwardly in the manner shown in FIG. 7. The guard 4, however,remains locked at the forward end of the housing 1 by engagement of itscatch 57 against the rear edge 15 of the recess 14. The cannula assembly3 can now be released from the housing 1 by twisting the housing through90° so that the enlarged regions 56 in the aperture 54 of the guard 4align with the lugs 45 on the cannula assembly 3.

When the needle assembly 2 is retracted rearwardly to its full extent,which is limited by engagement with the stop 18, the catch 24 on theneedle assembly snaps into the aperture 16 so that subsequent forwarddisplacement of the needle assembly is prevented by engagement of thecatch with the forward edge 17. In this position, the tip 19 of theneedle 20 is located beneath the horizontal plate 50 of the guard 4,about midway along its length so that access is prevented to the needletip through the slot 12 in the housing 1. If the needle were bentupwardly, in its extended position, the tip 19 would still be retainedbelow the guard 4 when retracted, in contrast with some previous needleprotection assemblies.

In an alternative arrangement, as shown in FIG. 9, the floor of thehousing 1' could have a series of rearwardly inclined ratchet teeth 60,which allow rearward displacement of the needle hub 21 but preventforward displacement, at any position along the housing, by engagementof the catch 24 on the rear surfaces of the teeth.

It will be appreciated that the invention is not confined to intravenousneedle assemblies.

I claim:
 1. A needle protection assembly including a channel-shapeprotector housing having a slot opening along a major part of the lengthof the housing, a needle assembly slidable along the housing between afirst position in which a tip of a needle is located within the housingand a second position in which the tip of the needle is exposed at oneend of the housing, a cannula assembly mounted on the needle assemblysuch that it can be slid off the tip of the needle in the secondposition, characterised in that the assembly includes a guard mounted onthe needle assembly such that it is displaced fowardly to the one end ofthe housing when the needle assembly is slid to the second position, anda lock for retaining the guard at the one end of the housing when theneedle assembly is retracted rearwardly to the first position, and thatthe guard covers the slot in the housing in the region of the tip of theneedle when the needle assembly is retracted to the first position. 2.An assembly according to claim 1, characterised in that the lockcomprises a resilient catch on the guard and a locking surface on thehousing.
 3. An assembly according to claim 2, characterised in that theresilient catch is a rearwardly-extending inclined tab.
 4. An assemblyaccording to claim 1, wherein the needle protection assembly includes asecond lock for locking the needle assembly in the first position afterit has been retracted into the first position.
 5. An assembly accordingto claim 4, characterised in that the second lock is provided by aforwardly-extending inclined tab on the needle assembly and arearwardly-facing locking surface on the housing.
 6. An assemblyaccording to claim 5 wherein when the guard is in the first position thetab on the needle assembly engages an upper surface of the tab on theguard so that when the needle assembly is slid forwardly the tab on theguard deflects the tab on the needle assembly over the rearwardly-facinglocking surface.
 7. An assembly according to any one of the precedingclaims, characterised in that the guard has a surface formation on anupper surface, that the needle assembly has a surface formation at oneend of an arm, that the arm extends from a catch resiliently-mounted onthe needle assembly, that the needle assembly is displaced from thefirst to the second position by engaging one surface of the catch sothat its arm is urged downwardly, and that the needle assembly isdisplaced from the second to the first position by engaging anothersurface of the catch so that its arm is urged upwardly and the surfaceformation on the arm clears the surface formation on the guard.
 8. Anassembly according to any one of claims 1 to 6, wherein the guard has alateral plate with a non-circular aperture, that the cannula assemblyextends through the aperture, and that the rear end of the cannulaassembly is shaped such that it can only pass through the aperture whenoriented correctly.
 9. An assembly according to any one of claims 1 to6, wherein the housing has a rail extending along its length, and thatthe needle assembly and guard both engage the rail.